Color prints obtained from images captured underwater are typically very disappointing to the consumer. When an image is captured underwater, red light is filtered out by the water. This filtering effect becomes even worse at greater depths and longer distance from the subject to the camera. This filtering results in prints made from these images to lack the appropriate amount of red. Available light photography becomes more difficult with depth as red light is filtered and the overall illumination becomes lower. This problem persists even when underwater illumination systems are provided because the red light is filtered by the amount of water between the light source and the subject, and then again as the reflected light returns to the camera. As a result, under exposures often suffer from poor image quality when reproduced by traditional systems.
The present approach to solving the problem of an image captured underwater includes over-exposing of the image. However, this only helps if the blue and green channels are not driven to clipping where the blue and green channels lose detail from saturation, and if compensation is made in the printing of the color negative. Placing a filter, such as a blue and green filter, over the camera's lens and metering system can help, but this decreases the overall light level and maintains a fixed ratio between the color channels. There has also been suggested the use of reversal film with an altered color balance. However, this is often costly in development and the fixed amplification ratio in the three color channels does not account for variations in depth and is subject to camera distance. While flash systems and other artificial lighting can be utilized, the distance between the subject and camera must be accounted for. While macro exposures are often used to minimize this distance problem, close-up photography may not be practical or desirable.
In co-pending U.S. patent application entitled "Method And Apparatus For Printing Digital Images" to John R. Fredlund, Ser. No. 09/248,967 filed Feb. 12, 1999, there is disclosed a method for automatically determining if an image was captured underwater and then compensating for this. While very helpful, this reference does not disclose or teach how to determine the depth at which the image was captured or for compensating the correction to the image based on such information.
Thus, there exists a need to improve the quality of prints made from images captured underwater in an efficient and accurate manner.